Section 18 AAC 80.035 - Disinfection of water from a source other than surface water, GWUDISW, or groundwater(a) This section applies to a public water system that (2) is a seawater system; or(3) has any other source of water that is not classified as surface water, GWUDISW, or groundwater.(b) The department will require the owner of a public water system to install and maintain continuous disinfection if the department determines that continuous disinfection is necessary to protect public health and (1) the department is aware of a condition that poses a threat to the microbiological quality of water;(2) the system is in violation of the MCL for Escherichia coli bacteria set by 40 C.F.R. 141.63(c) and (d), adopted by reference in 18 AAC 80.010(a); or(3) the department determines that a significant potential exists for violation of the MCL for Escherichia coli bacteria set by 40 C.F.R. 141.63(c) and (d), adopted by reference in 18 AAC 80.010(a).(c) The operator of a public water system for which disinfection is required under (b) of this section shall (1) monitor the system daily to maintain a residual disinfectant concentration of not less than 0.2 mg/l in the water entering the distribution system; if the residual disinfectant concentration in a system using grab sampling instead of continuous monitoring falls below 0.2 mg/l, the operator shall take a grab sample at least every four hours until the concentration is raised to 0.2 mg/l or higher;(2) maintain a detectable residual disinfectant concentration in the distribution system, as follows: (A) the concentration must be measured at the same frequency and locations required for total coliforms in 18 AAC 80.400 - 18 AAC 80.425;(B) the concentration may not be undetectable in more than five percent of the samples each month for two consecutive months during which the system serves water to the public;(C) the heterotrophic plate count (HPC) may be measured as described in 18 AAC 80.1103(6) instead of residual disinfectant concentration; water in the distribution system with a heterotrophic bacteria density less than or equal to 500 per ml is considered a detectable residual for purposes of determining compliance with this paragraph; and(3) report the monitoring results required by this section to the department within 10 days after the last day of each month during which the system serves water to the public, subject to the report certification requirements of 18 AAC 80.1900.Eff. 10/1/99, Register 151; am 3/25/2001, Register 157; am 11/9/2006, Register 180; am 4/24/2009, Register 190; am 7/25/2010, Register 195; am 5/20/2011, Register 198; am 2/11/2017, Register 221, April 2017Authority:AS 46.03.020
AS 46.03.050
AS 46.03.710
AS 46.03.720